* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
* This code is derived from software contributed to Berkeley by
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* @(#)btree.h 8.1 (Berkeley) 6/4/93
#define DEFMINKEYPAGE (2) /* Minimum keys per page */
#define MINCACHE (5) /* Minimum cached pages */
#define MINPSIZE (512) /* Minimum page size */
* Page 0 of a btree file contains a copy of the meta-data. This page is also
* used as an out-of-band page, i.e. page pointers that point to nowhere point
* to page 0. Page 1 is the root of the btree.
#define P_INVALID 0 /* Invalid tree page number. */
#define P_META 0 /* Tree metadata page number. */
#define P_ROOT 1 /* Tree root page number. */
* There are five page layouts in the btree: btree internal pages (BINTERNAL),
* btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
* (RLEAF) and overflow pages. All five page types have a page header (PAGE).
* This implementation requires that longs within structures are NOT padded.
* (ANSI C permits random padding.) If your compiler pads randomly you'll have
* to do some work to get this package to run.
pgno_t pgno
; /* this page's page number */ pgno_t prevpg
; /* left sibling */ pgno_t nextpg
; /* right sibling */#define P_BINTERNAL 0x01 /* btree internal page */
#define P_BLEAF 0x02 /* leaf page */
#define P_OVERFLOW 0x04 /* overflow page */
#define P_RINTERNAL 0x08 /* recno internal page */
#define P_RLEAF 0x10 /* leaf page */
#define P_TYPE 0x1f /* type mask */
#define P_PRESERVE 0x20 /* never delete this chain of pages */
indx_t lower
; /* lower bound of free space on page */ indx_t upper
; /* upper bound of free space on page */ indx_t linp
[1]; /* long-aligned VARIABLE LENGTH DATA *//* First and next index. */
#define BTDATAOFF (sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) + \
sizeof(u_long) + sizeof(indx_t) + sizeof(indx_t))
#define NEXTINDEX(p) (((p)->lower - BTDATAOFF) / sizeof(indx_t))
* For pages other than overflow pages, there is an array of offsets into the
* rest of the page immediately following the page header. Each offset is to
* an item which is unique to the type of page. The h_lower offset is just
* past the last filled-in index. The h_upper offset is the first item on the
* page. Offsets are from the beginning of the page.
* If an item is too big to store on a single page, a flag is set and the item
* is a { page, size } pair such that the page is the first page of an overflow
* chain with size bytes of item. Overflow pages are simply bytes without any
* The size and page number fields in the items are long aligned so they can be
* manipulated without copying.
#define LALIGN(n) (((n) + sizeof(u_long) - 1) & ~(sizeof(u_long) - 1))
#define NOVFLSIZE (sizeof(pgno_t) + sizeof(size_t))
* For the btree internal pages, the item is a key. BINTERNALs are {key, pgno}
* pairs, such that the key compares less than or equal to all of the records
* on that page. For a tree without duplicate keys, an internal page with two
* consecutive keys, a and b, will have all records greater than or equal to a
* and less than b stored on the page associated with a. Duplicate keys are
* somewhat special and can cause duplicate internal and leaf page records and
* some minor modifications of the above rule.
typedef struct BINTERNAL
{
size_t ksize
; /* key size */
pgno_t pgno
; /* page number stored on */#define P_BIGDATA 0x01 /* overflow data */
#define P_BIGKEY 0x02 /* overflow key */
char bytes
[1]; /* data */
/* Get the page's BINTERNAL structure at index indx. */
#define GETBINTERNAL(pg, indx) \
((BINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
/* Get the number of bytes in the entry. */
#define NBINTERNAL(len) \
LALIGN(sizeof(size_t) + sizeof(pgno_t) + sizeof(u_char) + (len))
/* Copy a BINTERNAL entry to the page. */
#define WR_BINTERNAL(p, size, pgno, flags) { \
* For the recno internal pages, the item is a page number with the number of
* keys found on that page and below.
typedef struct RINTERNAL
{
recno_t nrecs
; /* number of records */ pgno_t pgno
; /* page number stored below *//* Get the page's RINTERNAL structure at index indx. */
#define GETRINTERNAL(pg, indx) \
((RINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
/* Get the number of bytes in the entry. */
LALIGN(sizeof(recno_t) + sizeof(pgno_t))
/* Copy a RINTERAL entry to the page. */
#define WR_RINTERNAL(p, nrecs, pgno) { \
/* For the btree leaf pages, the item is a key and data pair. */
size_t ksize
; /* size of key */
size_t dsize
; /* size of data */
u_char flags
; /* P_BIGDATA, P_BIGKEY */ char bytes
[1]; /* data */
/* Get the page's BLEAF structure at index indx. */
#define GETBLEAF(pg, indx) \
((BLEAF *)((char *)(pg) + (pg)->linp[indx]))
/* Get the number of bytes in the entry. */
#define NBLEAF(p) NBLEAFDBT((p)->ksize, (p)->dsize)
/* Get the number of bytes in the user's key/data pair. */
#define NBLEAFDBT(ksize, dsize) \
LALIGN(sizeof(size_t) + sizeof(size_t) + sizeof(u_char) + \
/* Copy a BLEAF entry to the page. */
#define WR_BLEAF(p, key, data, flags) { \
*(size_t *)p = key->size; \
*(size_t *)p = data->size; \
memmove(p, key->data, key->size); \
memmove(p, data->data, data->size); \
/* For the recno leaf pages, the item is a data entry. */
size_t dsize
; /* size of data */
u_char flags
; /* P_BIGDATA *//* Get the page's RLEAF structure at index indx. */
#define GETRLEAF(pg, indx) \
((RLEAF *)((char *)(pg) + (pg)->linp[indx]))
/* Get the number of bytes in the entry. */
#define NRLEAF(p) NRLEAFDBT((p)->dsize)
/* Get the number of bytes from the user's data. */
#define NRLEAFDBT(dsize) \
LALIGN(sizeof(size_t) + sizeof(u_char) + (dsize))
/* Copy a RLEAF entry to the page. */
#define WR_RLEAF(p, data, flags) { \
*(size_t *)p = data->size; \
memmove(p, data->data, data->size); \
* A record in the tree is either a pointer to a page and an index in the page
* or a page number and an index. These structures are used as a cursor, stack
* entry and search returns as well as to pass records to other routines.
* One comment about searches. Internal page searches must find the largest
* record less than key in the tree so that descents work. Leaf page searches
* must find the smallest record greater than key so that the returned index
* is the record's correct position for insertion.
* One comment about cursors. The cursor key is never removed from the tree,
* even if deleted. This is because it is quite difficult to decide where the
* cursor should be when other keys have been inserted/deleted in the tree;
* duplicate keys make it impossible. This scheme does require extra work
* though, to make sure that we don't perform an operation on a deleted key.
pgno_t pgno
; /* the page number */ indx_t index
; /* the index on the page */ PAGE
*page
; /* the (pinned) page */ indx_t index
; /* the index on the page */ * The metadata of the tree. The m_nrecs field is used only by the RECNO code.
* This is because the btree doesn't really need it and it requires that every
* put or delete call modify the metadata.
u_long m_magic
; /* magic number */ u_long m_version
; /* version */ u_long m_psize
; /* page size */ u_long m_free
; /* page number of first free page */ u_long m_nrecs
; /* R: number of records */#define SAVEMETA (B_NODUPS | R_RECNO)
u_long m_flags
; /* bt_flags & SAVEMETA */ u_long m_unused
; /* unused *//* The in-memory btree/recno data structure. */
MPOOL
*bt_mp
; /* memory pool cookie */ DB
*bt_dbp
; /* pointer to enclosing DB */ EPGNO bt_bcursor
; /* B: btree cursor */ recno_t bt_rcursor
; /* R: recno cursor (1-based) */#define BT_POP(t) (t->bt_sp ? t->bt_stack + --t->bt_sp : NULL)
#define BT_CLR(t) (t->bt_sp = 0)
EPGNO
*bt_stack
; /* stack of parent pages */ u_int bt_sp
; /* current stack pointer */ u_int bt_maxstack
; /* largest stack */ char *bt_kbuf
; /* key buffer */
size_t bt_kbufsz
; /* key buffer size */
char *bt_dbuf
; /* data buffer */
size_t bt_dbufsz
; /* data buffer size */
int bt_fd
; /* tree file descriptor */
pgno_t bt_free
; /* next free page */ u_long bt_psize
; /* page size */ indx_t bt_ovflsize
; /* cut-off for key/data overflow */ int bt_lorder
; /* byte order */
enum { NOT
, BACK
, FORWARD
, } bt_order
;
EPGNO bt_last
; /* last insert */ /* B: key comparison function */
int (*bt_cmp
) __P((const DBT
*, const DBT
*));
/* B: prefix comparison function */
int (*bt_pfx
) __P((const DBT
*, const DBT
*));
/* R: recno input function */
int (*bt_irec
) __P((struct BTREE
*, recno_t
));
FILE *bt_rfp
; /* R: record FILE pointer */
int bt_rfd
; /* R: record file descriptor */
caddr_t bt_cmap
; /* R: current point in mapped space */ caddr_t bt_smap
; /* R: start of mapped space */ caddr_t bt_emap
; /* R: end of mapped space */ size_t bt_msize
; /* R: size of mapped region. */
recno_t bt_nrecs
; /* R: number of records */ size_t bt_reclen
; /* R: fixed record length */
u_char bt_bval
; /* R: delimiting byte/pad character */ * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
#define B_DELCRSR 0x00001 /* cursor has been deleted */
#define B_INMEM 0x00002 /* in-memory tree */
#define B_METADIRTY 0x00004 /* need to write metadata */
#define B_MODIFIED 0x00008 /* tree modified */
#define B_NEEDSWAP 0x00010 /* if byte order requires swapping */
#define B_NODUPS 0x00020 /* no duplicate keys permitted */
#define B_RDONLY 0x00040 /* read-only tree */
#define B_SEQINIT 0x00100 /* sequential scan initialized */
#define R_CLOSEFP 0x00200 /* opened a file pointer */
#define R_EOF 0x00400 /* end of input file reached. */
#define R_FIXLEN 0x00800 /* fixed length records */
#define R_MEMMAPPED 0x01000 /* memory mapped file. */
#define R_RECNO 0x00080 /* record oriented tree */
#define R_INMEM 0x02000 /* in-memory file */
#define R_MODIFIED 0x04000 /* modified file */
#define R_RDONLY 0x08000 /* read-only file */
u_long bt_flags
; /* btree state */#define SET(t, f) ((t)->bt_flags |= (f))
#define CLR(t, f) ((t)->bt_flags &= ~(f))
#define ISSET(t, f) ((t)->bt_flags & (f))
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